Some clinicians now advocate dentinal etching to eliminate microleakage around composite resin margins. This study evaluated the Kanca technique and three commercial dentinal adhesives, including Clearfil Photo Bond, which uses phosphoric acid to etch dentin. The Kanca technique and Tenure were the most effective systems tested. However, none of the bonding systems completely eliminated microleakage. Total sealing of dentinal margins is not predict able with current adhesives and composite resins.